Structural Characterization of Lignin and Its Degradation Products with Spectroscopic Methods

Table 4

Assignments of signals in ¹³C NMR spectrum to functional groups in lignin [31, 38, 49, 71].

Chemical shift/ppm	Assignments
167–178	Unconjugated -COOH
162–168	Conjugated -COOH
140–155	C3, C4 aromatic ether or hydroxyl
127–140	C1, aromatic C-C
123–127	C5, aromatic C-C
117–123	C6, aromatic C-H
114–117	C5, aromatic C-H
106–114	C2, aromatic C-H
78–90	Aliphatic Cβ-O
67–78	Aliphatic Cα-O
54–57.5	Methoxyl